Fragrance Compounds

ABSTRACT

A method of providing a fragrant odour to an application, comprising the addition thereto of at least one compound of the formula (I) wherein X and Y are independently selected from the group consisting of —CR 1 R 2 R 3 , —NR 4 R 5  and —OR 6 , wherein R 1  to R 5  are selected from H and essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom, and R 6  is selected from essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom; and A is an essentially hydrocarbon moiety that optionally comprises at least one oxygen, sulphur, nitrogen or silicon atom, with the proviso that the compound A-CHO is a fragrant aldehyde. The use of these compounds in laundry, household and personal care products confers a long-lasting freshness.

This invention relates to the provision of fragrance and to a process and compounds for achieving this.

The provision of fragrance by the addition of inherently fragrant substances to products is well known and widely used. An alternative method of providing fragrance is by the use of a precursor, that is, a substance that is not itself fragrant, but which, in particular circumstances, for example exposure to light, pH change and enzymatic activity, will break down to give at least one fragrant substance.

It has now been discovered that a particular class of substances can act as precursors by providing a source of at least one fragrant aldehyde. The invention therefore provides a method of providing a fragrant odour to an application, comprising the addition thereto of at least one compound of the formula I

wherein X and Y are independently selected from the group consisting of —CR¹R²R³, —NR⁴R⁵ and —OR⁶, wherein R¹ to R⁵ are selected from H and essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom, and R⁶ is selected from essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom; and A is an essentially hydrocarbon moiety that optionally comprises at least one oxygen, sulphur, nitrogen or silicon atom, with the proviso that the compound A-CHO is a fragrant aldehyde.

The invention additionally provides use of a compound of Formula I as hereinabove defined as a precursor of a fragrance.

By “essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom” (and, in the case of A, also at least one sulphur atom) is meant that the moieties X, Y and A are at least predominantly hydrocarbon in nature, that is, that the moieties will comprise mainly carbon and hydrogen, and that the number of carbon atoms present on a given moiety is greater than that of any oxygen, nitrogen and silicon (and, in the case of A, sulphur) atoms present. Thus, if there is present one oxygen atom, there must be present at least two carbon atoms on the moiety. The oxygen, nitrogen, sulphur and silicon atoms may either form part of the otherwise hydrocarbon chain, or they may be linked to carbon atoms on the chain, either directly (for example, a carbonyl group oxygen or a hydroxyl group) or as part of a substituent (for example, a nitrile group).

The wavy bond to the hydrogen means that the arrangement at the ethylenic double bond may be either in the E- or the Z-configuration. In individual instances, depending on the natures of X and Y, one or other isomer may be preferred, but this is not usually the case. With regard to X and Y, there may be present stereogenic units such as chiral centres or substituted double bonds, which result in there existing several different stereoisomers. In some cases, these can result in odours of different strengths or even characters, and these can be separated by conventional techniques, if desired. However, this adds to the complexity (and therefore the expense), and it is generally preferred to leave the compounds as a mixture of stereoisomers.

A is defined by the requirement that A-CHO is a fragrant aldehyde. Such molecules are well known to the art. Examples of fragrant aldehydes from which the moiety A may be derived include, but are not limited to, the following:

-   2,6,10-trimethylundec-9-enal, -   8,8-dimethyl-1,2,3,4,5,6,7,8-octahydro-naphthalene-2-carbaldehyde, -   (4-isopropyl-phenyl)-ethanal, -   2,4-dimethyl-cyclohex-3-ene-1-carbaldehyde, -   1,3,5-trimethyl-cyclohex-1-ene-4-carbaldehyde, -   4-(4-hydroxy-4-methylpentyl)-cyclohex-3-ene-1-carbaldehyde, -   hex-2-enal, -   3,5,5-trimethyl-hexanal, -   heptanal, -   2,6-dimethyl-hept-5-enal, -   decanal, -   dec-9-enal, -   dec-4-en-1-al, -   2-methyl-decanal, -   undec-10-en-1-al, -   undecanal, -   dodecanal, -   2-methyl-undecanal, -   tridecanal, -   tridec-2-enal, -   octanal, -   nonanal, -   non-2-enal, -   undec-9-enal, -   2-phenyl-propanal, -   2-(4-methyl-phenyl)-ethanal, -   3,7-dimethyl-octanal, -   dihydrofarnesal, -   7-hydroxy-3,7-dimethyl-octanal, -   2,6-dimethyl-oct-5-en-1-al, -   3-(3-isopropyl-phenyl)-butanal -   2-(3,7-dimethyl-oct-6-en-oxy)-ethanal, -   4-(4-methyl-pent-3-enyl)-cyclohex-3-ene-1-carbaldehyde, -   2,3,5,5,-tetramethyl-hexanal, -   longifolic aldehyde, -   2-methyl-4-(2,6,6-trimethylcyclohex-2-en-1-yl)-butanal, -   2-methyl-3-(4-tert-butylphenyl)-propanal, -   3-(4-tert-butyl-phenyl)-propanal, -   2-(4-isopropyl-phenyl)-propanal, -   3-(benzo[1,3]dioxol-5-yl)-2-methyl-propanal, -   3,7-dimethyl-oct-6-ene-1-al, -   2-methyl-3-(4-isopropylphenyl)-propanal, -   4-tert-butyl-cyclohexane-1-carbaldehyde, -   4-(octahydro-4,7-methano-5H-inden-5-ylidene)-butanal, -   (3,7-dimethyl-oct-6-enyloxy)-ethanal, -   (2E,6Z)-nonadienal, -   2,4-dimethyl-2,6-heptadienal, -   (E)-dec-2-enal, -   dodec-2-enal, -   3,7-dimethyl-octa-2,6-dienal, -   2,4-diethyl-hepta-2,6-dienal, -   3,7-dimethyl-nona-2,6-dienal, -   3-propyl-hept-2-enal, and -   4-isopropenyl-cyclohex-1-ene-1-carbaldehyde.

In particular embodiments, X and Y are independently selected from the following moieties:

(a) C₁-C₂₀ alkyl, linear or branched, optionally containing oxygen, nitrogen or silicon atoms, such as methyl, ethyl, propyl, butyl, isobutyl, 2-ethylhexyl, tert.-butyl; (b) cyclopropyl, cyclopentyl, cyclohexyl, cyclooctyl; optionally containing oxygen, nitrogen or silicon atoms, such as tetrahydrofuranyl, pyranyl, piperidinyl, pyrrolidinyl; (c) C₃-C₂₀ alkylcycloalkyl, optionally containing oxygen, nitrogen or silicon atoms, such as methylcyclohexyl, ethylcyclohexyl, methylcyclopentyl; (d) C₆-C₂₀ cycloalkylalkyl optionally containing oxygen, nitrogen or silicon atoms, such as (4-methyl)-cyclohexyl, (e) C₃-C₁₀ alkenyl, linear or branched, optionally containing oxygen, nitrogen or silicon atoms, such as propenyl, isopropenyl, isobutenyl; (f) C₆-C₁₀ aryl with optional substituents, such as phenyl, o- or p-methoxyphenyl; (g) C₇-C₁₀ alkylaryl with optional substituents and containing optionally oxygen, nitrogen or silicon atoms, such as benzyl, methoxybenzyl; (g) C₅-C₁₀ heteroaryl, such as pyridinyl, furanyl, pyrryl, imidazolyl; (h) —OR⁶, wherein R⁶ is C₁-C₂₀ alkyl, linear or branched, optionally containing oxygen, nitrogen or silicium atoms, such as methyl, ethyl, propyl, butyl, isobutyl, 2-ethylhexyl, tert.-butyl; or cyclopentyl, cyclohexyl; or C₃-C₁₀ alkenyl, linear or branched, such as propenyl, isopropenyl, isobutenyl; or C₆-C₈ aryl, such as phenyl or naphtyl; and (i) —NR⁴R⁵, wherein R⁴ and R⁵ are, independently of each other, H; C₁-C₂₀ alkyl, linear or branched, such as methyl, ethyl, propyl, butyl, isobutyl, 2-ethylhexyl, optionally containing oxygen or nitrogen atoms; or cyclopentyl, cyclohexyl; alternatively NR⁴R⁵ form together a 3-, 5- or 6-membered ring. and A is selected from the group consisting of C₇-C₁₇ linear or branched alkyl, cycloalkyl, alkylcycloalkyl or cycloalkylalkyl, C₇-C₁₅ linear or branched alkenyl, and C₆-C₁₀ aryl.

One way of preparing the compounds is via a Knoevenagel condensation, in which a fragrant aldehyde is reacted with a suitable 1,3-dicarbonyl compound in the presence of a suitable catalyst, such as secondary amines, for example, piperidine, pyrrolidine, dimethylamine, diethylamine, or ammonium salts, for example, ammonium acetate and ethylene diamine diacetate. Many other catalysts do promote this reaction and are known to the person skilled in the art of organic synthesis. The reaction is depicted schematically below:

As the groups X and Y of the 1,3-dicarbonyl compound

play no part in the reaction, the compound may be chosen from a very wide variety of such materials. Specific examples of 1,3-dicarbonyl compounds include ethyl 3-oxobutanoate, ethyl 3-oxo-3-phenylpropanoate, benzyl 3-oxobutanoate, diethyl malonate, dimethyl malonate, diisopropyl malonate, dibenzyl malonate, 1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-propane-1,3-dione (Parsol™ 1789) and ethyl 1-(3,3-dimethylcyclohexyl)ethyl malonate (Musk Nouvelle™, (IFF)).

Specific examples of compounds include the following:

While some of these compounds are known (but not for this particular purpose), others are novel. For example, in the formulae depicted above, Nos. (iv), (v), (vii), (xi)-(xxvii) and (xx) are novel. The invention therefore also provides a compound of the formula I

wherein i) X and Y are the same and are selected from

-   -   a) —OR⁶, wherein R⁶ is selected from the group consisting of         methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl,         benzyl; or     -   b) phenyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl;         or         ii) X and Y are different, and are selected according to the         following table:

X Y Me OMe, OEt, O-tBu, O-iPr, OBn, O-cis-3- hexenyl Me Et, Pr, Bu, Pent Ph OMe, OEt 2-(1-(3,3-dimethyl- OEt cyclohexyl)ethoxy and; A is selected from branched or linear C₇-C₁₅ alkyl and C₇-C₁₅ alkenyl moieties, these optionally comprising oxygen atoms present as ether, hydroxyl, carbonyl or ester moieties.

All of the compounds of formula I hereinabove described have in common the fact that, on exposure to moisture, either liquid water applied to the compounds or to a support on which they have been deposited, or water vapour in the atmosphere, they release a fragrant aldehyde.

As previously mentioned, the groups X and Y of the 1,3-dicarbonyl compound

play no part in the reaction, and they may be chosen from a very wide variety of such materials. However, in a further aspect of the invention, they can be chosen such that the compound, once separated from the fragrant aldehyde, performs a desired function. For example, the compound itself may have fragrant characteristics, either as a fragrant material in its own right, or as a modifier for the fragrant aldehyde, or other fragrant material also present in a composition in which the compound useful in the invention is used. Another possibility is that it may enhance substantivity or stability in a given application. A third possibility is that it perform an entirely independent function in a composition. For example, it may act as a sunscreen, thus, for example, supplying a cosmetic composition simultaneously with a fragrance and a protective function. The skilled person will readily comprehend that there are many other possible uses, and will be able to tailor the 1,3-dicarbonyl compound appropriately to perform any such function.

The invention is useful for providing a fragrant odour to an application where release of the odour is desired at some particular time point and is caused by the presence of moisture. “Application” in the context of this invention means any use in which such an effect is desired. Examples include laundry use (release in a wash liquor, in a dryer or on laundry post-drying), use in hard surface cleaners, cosmetics, protective creams, personal care products, such as hair care products, skin creams and lotions, fine fragrances and air-care products, such as air fresheners.

In use, the compounds may be combined with any other suitable free fragrance material. For example, they may be combined with free fragrance aldehydes, so that the free fragrance delivers an immediate impact and the compounds of the invention provide a lasting fragrance. By using the compounds of the present invention, the strong floral-fresh impact of many fragrant aldehydes, which by themselves are not substantive, can be prolonged in many applications where such long-lasting freshness is desired, without having to overdose the aldehydes in the perfume. This opens new possibilities for fragrance creation.

The compounds for use in this invention may be incorporated into commercial products in conventional proportions and by art-recognised methods. Commercial products include washing and laundry detergents, fabric softeners and conditioners, personal care products, such as hair and skin care preparations, soaps and lotions. They may be incorporated directly into such compositions, or they may be added in conjunction with a carrier, such as microcapsules, adsorbed on to suitable particulate matter or spray-dried.

One of the particular features of this invention is that, if the Knoevenagel synthesis hereinabove described is used, the compounds need not be made in a manufacturing plant and shipped to the user, but they may be made in situ. They can thus be made simply and easily on site and then added directly to the composition in which their presence is desired. This confers a considerable versatility, in that it allows a user to make a desired compound on the spot, without waiting for a delivery. The invention therefore also provides a process of manufacturing a fragranced composition, in which the fragrance is gradually released on exposure to moisture, comprising the steps of

(a) blending a compound of the formula II

wherein X and Y are as hereinabove defined, with a fragrant aldehyde in the presence of a base under such conditions that a Knoevenagel condensation takes place; and (b) adding the product of (a) to the composition.

Conditions allowing a Knoevenagel condensation to take place in situ, i.e. step a) in the above-described process, include also thermal dehydration methods such as spray-drying. Therein, the mixture of a compound of formula II, together with one or several fragrant aldehydes and a base are formulated into an aqueous emulsion, containing optional carrier materials and surfactants. This emulsion is then spray-dried, thereby producing solid particles containing products of formula I.

The invention is now further described with reference to the following non-limiting examples, which describe preferred embodiments.

EXAMPLE 1 Preparation of 2-benzoyl-dec-2-enoic Acid Ethyl Ester, a Compound According to the Formula

Piperidine (0.10 ml, 0.5 mol %) is added to a mixture of octanal (25.6 g, 0.20 mol) and ethyl benzoylacetate (38.4 g, 0.20 mol) at 5° C. The resulting solution is warmed to room temperature and stirred for 24 h, during which a fine emulsion is formed. The mixture is diluted with methyl t-butyl ether and the organic layer washed with 2 N aq. HCl-solution, water and brine, then dried over MgSO₄.

The solvent is removed in vacuo and the residue distilled to yield 18.0 g (38%) of product as an E/Z-mixture, boiling at 129-135° C./0.1 mbar.

¹³C-NMR (CHCl₃, 100 MHz; main isomer): 194.5 (s), 164.6 (s), 148.6 (d), 137.2 (s), 133.7 (d), 133.6 (s), 129.0 (d), 128.8 (d), 61.0 (t), 31.6 (t), 29.5 (t), 29.1 (t), 28.8 (t), 28.3 (t), 22.5 (t), 14. (q), 13.9 (q).

MS (EI, 70 eV): 302 (<1, M⁺), 257 (2), 217 (10), 199 (15), 186 (15), 171 (4), 157 (13), 105 (100).

EXAMPLES 2-12

The following compounds are made by a method according to claim 1, using the appropriate fragrant aldehyde and 1,3-dicarbonyl compound:

b. p. (if distilled) ¹³ C-NMR [° C./ CDCl₃, 100 MHz MS N° Structure mbar] (only main isomer) EI, 70 eV 2

127/0.07 194.9 (s), 166.5 (s), 147.5 (d), 139.8 (s), 131.6 (s), 124.2 (d), 59.4 (t), 39.5 (t), 35.3 (t), 32.3 (d), 27.4 (t), 25.7 (q), 22.4 (q), 19.6 266 (29, M⁺), 221 (27), 205 (26), 177 (29), 149 (20), 43 3

168- 171° C./ 0.08 195.0 (s), 168.8 (s), 149.3 (d), 136.6 (s), 71.8 (t), 70.4 (t), 68.9 (t), 63.5 (t), 58.9 (q), 32.5 (t), 30.0 (t), 29.2 (t), 29.0 (t), 27.0 (t), 22.5 (t), 27.0 (q), 14.0 (q). 272 (<1), 239 (7), 195 (17), 137 (45) 124 (27), 59 (94), 45 (100). 4

(purified by chroma- tography) 194.1 (s), 192.8 (s), 163.9 (s), 156.2 (s), 147.9 (d), 141.9 (s), 133.3 (s), 131.7 (d), 130.3 (s), 129.5 (d), 125.4 (d), 13.7 (d), 55.5 (q), 35.1 (s), 31.6 (t), 31.1 (q), 31.0 (t), 31.0 (t), 29.2 (t), 28.9 (t), 22.5 (t), 14.0 (q). 420 (24, M⁺), 363 (95) 335 (39), 279 (36), 255 (35), 161 (91), 150 (97), 135 (100). 5

(purified by chroma- tography) 165.3 (s), 163.8 (s), 151.1 (d), 135.6 (s), 135.4 (s), 128.5 (d), 128.4 (d), 128.3 (d), 128.2 (d), 128.0 (d), 128.0 (d), 67.0 (t), 66.9 (t), 31.7 (t), 29.9 (t), 29.2 (t), 28.9 (t), 28.3 (t), 22.6 (t), 14.1 (q). 394 (5, M⁺), 200 (16), 197 (20), 179 (77), 123 (15), 109 (12), 91 (100). 6

(purified by chroma- tography) 166.8 (s), 166.2 (s), 155.3 (d), 127.3 (s), 52.3 (q), 31.6 (t), 30.4 (t), 30.0 (t), 29.2 (t), 28.9 (t), 22.6 (t), 14.0 (q). 227 (3, M⁺), 210 (19), 178 (39), 168 (37), 153 (62), 139 (65), 113 (92), 81 (93), 41 (100). 7

(purified by chroma- tography) m. p. 126- 128° C. 206.4 (s), 196.4 (s), 148.4 (s), 146.0 (s), 140.6 (s), 140.1 (d), 125.0 (s), 125.0 (d), 114.9 (d), 112.2 (d), 64.6 (t), 31.7 (q), 26.3 (q), 14.7 (q). 248 (30, M⁺), 233 (8), 219 (4), 205 (11), 191 (11), 177 (11), 163 (25), 145 (11), 43 (100). 8

(purified by chroma- tography, only Z- isomer described) 201.2 (s), 164.4 (s), 152.3 (d), 149.2 (s), 136.3 (s), 134.9 (s), 128.9 (d), 125.2 (d), 61.1 (t), 42.4 (t), 36.5 (d), 34.4 (s), 31.3 (q), 30.5 (q), 19.9 (q), 14.1 (q). 316 (<1, M⁺), 298 (3), 270 (8), 147 (100). 9

(purified by chroma- tography) 165.4 (s), 164.1 (s), 152.9 (d), 152.6 (d), 148.9 (s), 135.8 (s), 135.6 (s), 129.0 (d), 128.8 (d), 128.7 (d), 128.6 (d), 128.2 (d), 127.8 (d), 127.7 (d), 125.2 (d), 76.2 (d), 61.1 (t), 41.6 (t), 41.6 (t), 41.2 (s, 1 C), 41.1 (t), 39.1 (t), 39.0 (t), 38.3 (d), 38.2 (d), 38.2 (d), 36.1 (d), 35.8 (d), 34.3 (s), 33.5 (q), 33.4 (q), 31.3 (q), 30.5 (s), 30.5 (s), 30.4 (s), 28.3 (t), 28.3 (t), 24.5 (q), 21.9 (t), 21.9 (t), 19.1 (q), 18.9 (q), 17.1 (q), 17.0 (q), 14.1 (q) 456 (2, M⁺), 318 (7), 300 (11), 147 (100). 10

(purified by chroma- tography) (only E-isomer described) 195.0 (s), 166.3 (s), 149.1 (s), 146.8 (d), 145.3 (s), 137.6 (s), 128.5 (d), 125.1 (d), 124.5 (d), 123.9 (d), 61.1 (t), 39.5 (d), 38.3 (t), 34.1 (d), 26.8 (q), 24.0 (q), 21.6 (q), 14.1 (q). 302 (<1, M⁺), 256 (9), 228 (5), 213 (5), 172 (9), 147 (100), 105 (20), 91 (14). 11

(purified by chroma- tography) (mixture of E and Z- isomers) 201.2 (s), 195.1 (s), 166.6 (s), 164.5 (s), 153.6 (d), 153.4 (d), 135.8 (s), 134.4 (s), 61.1 (t), 61.1 (s), 36.5 (t), 36.5 (t), 34.9 (d), 34.0 (d), 31.8 (t), 31.3 (t), 29.6 (t), 29.5 (t), 29.4 (t), 29.2 (t), 27.4 (t), 27.3 (t), 26.8 (q), 22.6 (t), 20.1 (q), 19.8 (q), 14.1 (q), 14.1 (q), 14.0 (q). 296 (<1, M⁺), 281 (2), 250 (71), 151 (42), 143 (26), 137 (50), 124 (18), 43 (100). 12

(purified by chroma- tography) 165.7 (s), 164.0 (s), 154.2 (d), 127.3 (s), 61.1 (t), 61.1 (t), 36.4 (t), 34.7 (d), 31.8 (t), 29.5 (t), 29.5 (t), 29.2 (t), 27.3 (t), 22.6 (t), 19.8 (q), 14.1 (q), 14.0 (q). 326 (<1, M⁺), 311 (<1), 297 (<1), 281 (23), 253 (4), 234 (100), 199 (9), 173 (59), 160 (62), 141 (41), 122 (85), 108 (86).

EXAMPLE 13 Application in Fabric Softener

To each of two samples of a standard unperfumed fabric softener base of the ester quat type is added one of the following:

-   -   1) 0.20% wt/wt of 2-methylundecenal     -   2) 0.32% wt/wt of ethyl 2-acetyl-4-methyltridec-2-enoate         (Example 11), equivalent to 0.20% wt/wt of 2-methylundecanal.

These bases are then added to the rinse cycle of a washing machine loaded with cotton terry towels. After centrifugation, the towels are evaluated olfactorily by a panel of trained evaluators. Odour scores are attributed to each towel at the given time, which are as follows: 0 (odourless), 1 (very weak), 2 (weak), 3 (medium), 4 (strong) and 5 (very strong). The arithmetic means of the scores from all evaluators are reported in the following table.

ethyl 2-acetyl-4- 2-methylundecanal methyltridec-2-enoate wet 5 2.1 1 d 0.3 3.6 2 d 0.9 4 6 d 0.3 3.8

From day 1 to day 6, the towel washed with the fabric softener base containing a compound according to the invention exhibits a strong 2-methylundecanal note, whereas the towels washed with base containing the free aldehyde are almost odourless.

EXAMPLE 14 Application in Liquid Detergent

To each of four samples of a standard unperfumed heavy duty liquid detergent base samples is added one of the following:

-   -   1) 0.20% wt/wt of 2-methylundecenal     -   2) 0.32% wt/wt of ethyl 2-acetyl-4-methyltridec-2-enoate         (Example 11), equivalent to 0.20% wt/wt of 2-methylundecanal.     -   3) 0.20% wt/wt of 3-(3-isopropylphenyl)butanal     -   4) 0.32% wt/wt of ethyl         2-acetyl-5-(3-isopropylphenyl)hex-2-enoate (Example 10),         equivalent to 0.20% wt/wt of 3-(3-isopropylphenyl)butanal)

Four individual 40° C. wash cycles are performed with the above samples, each with a load of cotton terry towels. Odour scores are attributed to the individual towels after time intervals by a panel of trained evaluators as described in example 3. The results are shown in the following table:

2-methyl- ethyl 2- 3-(3-isopropyl- 2-acetyl-5-(3- undecanal acetyl-4- phenyl)- isopropyl- (“Aldehyde methyltridec-2- butanal phenyl)- C12MNA”) enoate (“Florhydral”) hex-2-enoate wet 3.6 1.5 2.3 3.5 1 d 0 2.3 1.0 2.8 2 d 0 2.3 n.d. n.d. 3 d 0 2.4 n.d. n.d.

From wet to day 3, the towels washed with the liquid detergent base comprising a compound according to the invention exhibit a strong 2-methylundecanal note, whereas the towels washed with base containing the free aldehyde are almost weak to odourless. Likewise, the towels washed with 2-acetyl-5-(3-isopropylphenyl)hex-2-enoate exhibit a strong Florhydral note after 1 day on the dry towel, whereas the towel washed with free Florhydral has only a very weak smell. 

1. A method of providing a fragrant odour to an application, comprising the addition thereto of at least one compound of the formula I

wherein X and Y are independently selected from the group consisting of —CR¹R²R³, —NR⁴R⁵ and —OR⁶, wherein R¹ to R⁵ are selected from H and essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom, and R⁶ is selected from essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom; and A is an essentially hydrocarbon moiety that optionally comprises at least one oxygen, sulphur, nitrogen or silicon atom, with the proviso that the compound A-CHO is a fragrant aldehyde.
 2. Method according to claim 1, wherein the compound of Formula I is used as a precursor of a fragrance.
 3. Method according to claim 1, in which the fragrant aldehyde of the moiety A is selected from the group consisting of: 2,6,10-trimethylundec-9-enal, 8,8-dimethyl-1,2,3,4,5,6,7,8-octahydro-naphthalene-2-carbaldehyde, (4-isopropyl-phenyl)-ethanal, 2,4-dimethyl-cyclohex-3-ene-1-carbaldehyde, 1,3,5-trimethyl-cyclohex-1-ene-4-carbaldehyde, 4-(4-hydroxy-4-methylpentyl)-cyclohex-3-ene-1-carbaldehyde, hex-2-enal, 3,5,5-trimethyl-hexanal, heptanal, 2,6-dimethyl-hept-5-enal, decanal, dec-9-enal, dec-4-en-1-al, 2-methyl-decanal, undec-10-en-1-al, undecanal, dodecanal, 2-methyl-undecanal, tridecanal, tridec-2-enal, octanal, nonanal, non-2-enal, undec-9-enal, 2-phenyl-propanal, 2-(4-methyl-phenyl)-ethanal, 3,7-dimethyl-octanal, dihydrofarnesal, 7-hydroxy-3,7-dimethyl-octanal, 2,6-dimethyl-oct-5-en-1-al, 3-(3-isopropyl-phenyl)-butanal, 2-(3,7-dimethyl-oct-6-en-oxy)-ethanal, 4-(4-methyl-pent-3-enyl)-cyclohex-3-ene-1-carbaldehyde, 2,3,5,5,-tetramethyl-hexanal, longifolic aldehyde, 2-methyl-4-(2,6,6-rimethylcyclohex-2-en-1-yl)-butanal, 2-methyl-3-(4-tert-butylphenyl)-propanal, 3-(4-tert-butyl-phenyl)-propanal, 2-(4-isopropyl-phenyl)-propanal, 3-(benzo[1,3]dioxol-5-yl)-2-methyl-propanal, 3,7-dimethyl-oct-6-ene-1-al, 2-methyl-3-(4-isopropylphenyl)-propanal, 4-tert-butyl-cyclohexane-1-carbaldehyde, 4-(octahydro-4,7-methano-5H-inden-5-ylidene)-butanal, (3,7-dimethyl-oct-6-enyloxy)-ethanal, (2E,6Z)-nonadienal, 2,4-dimethyl-2,6-heptadienal, (E)-dec-2-enal, dodec-2-enal, 3,7-dimethyl-octa-2,6-dienal, 2,4-diethyl-hepta-2,6-dienal, 3,7-dimethyl-nona-2,6-dienal, 3-propyl-hept-2-enal, and 4-isopropenyl-cyclohex-1-ene-1-carbaldehyde.
 4. Method according to claim 1 in which X and Y are independently selected from the following moieties: (a) C₁-C₂₀ alkyl, linear or branched, optionally containing oxygen, nitrogen or silicon atoms; (b) cyclopropyl, cyclopentyl, cyclohexyl, cyclooctyl; optionally containing oxygen, nitrogen or silicon atoms. (c) C₃-C₂₀ alkylcycloalkyl, optionally containing oxygen, nitrogen or silicon atoms; (d) C₆-C₂₀ cycloalkylalkyl optionally containing oxygen, nitrogen or silicon atoms; (e) C₃-C₁₀ alkenyl, linear or branched, optionally containing oxygen, nitrogen or silicon atoms; (f) C₆-C₁₀ aryl with optional substituents; (g) C₇-C₁₀ alkylaryl with optional substituents and containing optionally oxygen, nitrogen or silicon atoms; (h) C₅-C₁₀ heteroaryl; (i) —OR⁶, wherein R⁶ is C₁-C₂₀ alkyl, linear or branched, optionally containing oxygen, nitrogen or silicon atoms; or C₃-C₁₀ alkenyl, linear or branched; or C₆-C₈ aryl; and (j) —NR⁴R⁵, wherein R⁴ and R⁵ are, independently of each other, H; C₁-C₂₀ alkyl linear or branched, optionally containing oxygen or nitrogen atoms; or cyclopentyl, cyclohexyl; or NR⁴R⁵ form together a 3-, 5- or 6-membered ring. and A is selected from the group consisting of C₇-C₁₇ linear or branched alkyl, cycloalkyl, alkylcycloalkyl or cycloalkylalkyl, C₇-C₁₅ linear or branched alkenyl, and C₆-C₁₀ aryl.
 5. A process of manufacturing a fragranced composition, in which the fragrance is gradually released on exposure to moisture, comprising the steps of (a) blending a compound of the formula II

in which X and Y are independently selected from the group consisting of —CR¹R²R³, —NR⁴R⁵ and —OR⁶, wherein R¹ to R⁵ are selected from H and essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom, and R⁶ is selected from essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom with a flagrant aldehyde in the presence of a base under such conditions that a Knoevenagel condensation takes place; and (b) adding the product of (a) to the composition.
 6. A compound according to Formula I

wherein i) X and Y are the same and are selected from a) —OR⁶, wherein R⁶ is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, benzyl; or b) phenyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl or ii) X and Y are different, and are selected according to the following table: X Y Me OMe, OEt, O-tBu, O-iPr, OBn, O-cis-3- hexenyl Me Et, Pr, Bu, Pent Ph OMe, OEt 2-(1-(3,3-dimethyl- OEt cyclohexyl)ethoxy

and; A is selected from branched or linear C₇-C₁₅ alkyl and C₇-C₁₅ alkenyl moieties, these optionally comprising oxygen atoms present as ether, hydroxyl, carbonyl or ester moieties.
 7. An application comprising known application ingredients and at least one compound of Formula I:

wherein X and Y are independently selected from the group consisting of —CR¹R²R³, —NR⁴R⁵ and —OR⁶, wherein R¹ to R⁵ are selected from H and essentially hydrocarbon moieties that optionally comprise at least one oxygen nitrogen or silicon atom, and R⁶ is selected from essentially hydrocarbon moieties that optionally comprise at least one oxygen, nitrogen or silicon atom; and A is an essentially hydrocarbon moiety that optionally comprises at least one oxygen, sulphur, nitrogen or silicon atom, with the proviso that the compound A-CHO is a fragrant aldehyde.
 8. Application according to claim 7, selected from laundry products, hard surface cleaners, cosmetics, protective creams, personal care products, cleansing products, hair care products, skin creams and lotions, fine fragrances and air-care products.
 9. Method according to claim 4 wherein the optional substituents comprise at least one of phenyl, o-methoxyphenyl or p-methoxyphenyl.
 10. Method according to claim 2 including combining the compound of Formula I with a free fragrance compound. 